I tried reading the rule book and it didn't say if there was a limit how many times you could do it. I assume there must be. Given a monster with an ignition effect, how many times can I activate it per turn?
Given a monster with an ignition effect, how many times can I activate it per turn?
Short answer is each card or monster will specify the number of times that you can activate their effects.
Usually this is written in the form of "Once per turn...", or "During your Main phase...". Some may say "twice", some even say "Once per Duel", etc..
In more general terms this is written in the form of:
"[Times it can be activated]+[Conditions needed to activate], [cost for activating]; [the effect]"